Use 32 bit key in TT

[stockfish] / src / tt.h

diff --git a/src/tt.h b/src/tt.h
index 31fc1fbce5f5a5801db869c86750028f2aa2c47e..4a8699fb2dfce4468d70b6e2a73889586d61e26d 100644 (file)
--- a/src/tt.h
+++ b/src/tt.h
@@ -1,7 +1,7 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008 Marco Costalba
+  Copyright (C) 2008-2009 Marco Costalba
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -34,14 +34,31 @@
 //// Types
 ////
 
-/// The TTEntry class is the class of transposition table entries.
+/// The TTEntry class is the class of transposition table entries
+///
+/// A TTEntry needs 96 bits to be stored
+///
+/// bit  0-31: key
+/// bit 32-63: data
+/// bit 64-79: value
+/// bit 80-95: depth
+///
+/// the 32 bits of the data field are so defined
+///
+/// bit  0-16: move
+/// bit 17-19: not used
+/// bit 20-22: value type
+/// bit 23-31: generation
 
 class TTEntry {
 
 public:
-  TTEntry();
-  TTEntry(Key k, Value v, ValueType t, Depth d, Move m, int generation);
-  Key key() const { return key_; }
+  TTEntry() {}
+  TTEntry(uint32_t k, Value v, ValueType t, Depth d, Move m, int generation)
+        : key_ (k), data((m & 0x1FFFF) | (t << 20) | (generation << 23)),
+          value_(int16_t(v)), depth_(int16_t(d)) {}
+
+  uint32_t key() const { return key_; }
   Depth depth() const { return Depth(depth_); }
   Move move() const { return Move(data & 0x1FFFF); }
   Value value() const { return Value(value_); }
@@ -49,7 +66,7 @@ public:
   int generation() const { return (data >> 23); }
 
 private:
-  Key key_;
+  uint32_t key_;
   uint32_t data;
   int16_t value_;
   int16_t depth_;
@@ -62,32 +79,29 @@ private:
 class TranspositionTable {
 
 public:
-  TranspositionTable(unsigned mbSize);
+  TranspositionTable();
   ~TranspositionTable();
   void set_size(unsigned mbSize);
   void clear();
-  void store(const Position &pos, Value v, Depth d, Move m, ValueType type);
-  TTEntry* retrieve(const Position &pos) const;
+  void store(const Key posKey, Value v, ValueType type, Depth d, Move m);
+  TTEntry* retrieve(const Key posKey) const;
   void new_search();
-  void insert_pv(const Position &pos, Move pv[]);
-  int full();
+  void insert_pv(const Position& pos, Move pv[]);
+  void extract_pv(const Position& pos, Move pv[]);
+  int full() const;
 
 private:
-  inline TTEntry* first_entry(const Position &pos) const;
+  inline TTEntry* first_entry(const Key posKey) const;
+
+  // Be sure 'writes' is at least one cacheline away
+  // from read only variables.
+  unsigned char pad_before[64 - sizeof(unsigned)];
+  unsigned writes; // heavy SMP read/write access here
+  unsigned char pad_after[64];
 
   unsigned size;
-  int writes;
   TTEntry* entries;
   uint8_t generation;
 };
 
-
-////
-//// Constants and variables
-////
-
-// Default transposition table size, in megabytes:
-const int TTDefaultSize = 32;
-
-
 #endif // !defined(TT_H_INCLUDED)